Many implantable medical devices require percutaneous communication. For example, devices which dispense drugs within the body require a supply provided by hypodermic needle injection through the skin. In devices such as implantable drug dispensers or catheter access ports, a needle is inserted through the skin, through a piereable septum on the drug dispenser, and into a reservoir where the drug is to be injected.
Since the medical device is installed subcutaneously, care must be taken to make sure that the needle is properly placed into the device before injection. If the needle misses the device, drug will be dispensed in the body either in an improper location or in improper amounts. If the needle does not properly peirce the septum, drug will not be dispensed adequately into the desired reservoir location.
Previous attempts have been made to provide notification of needle placement. These have involved complex apparatus such as the Celcontrol brand detector which requires the attachment of an electrode to the skin and the attachment of a wire to complete the circuit to the hypodermic needle. What is needed is a simpler technique for sensing needle position which does not require attachments to the skin or needle.